"It is a paranormal freak show" that features a "disturbing cast of characters," said Todd Patton, a co-creator.

Their story is that paranormal investigators discovered a book with special powers that "troubled the phantoms trapped deep within Lookout Mountain." Unearthing the book brought them back to life, the story goes.

Ruby Falls Haunted Cavern is open Sept. 30-Nov. 4, every Friday through Sunday in October except Oct. 2 and Halloween night. Hours are around 8 p.m. to 11 p.m. on Friday and Saturday nights (later if busy), until 10 p.m. on Sundays.

The attraction is not recommended for children under 11. Admission is $20 online, $22 at the door.

Ruby Falls is home to the tallest and deepest underground waterfall accessible to the public in the United States.